7.2 liter A/C Problem

[Blazeracer]

I have a 2001 7.3 liter. The air conditioning only seems to blow cold when the throttle is to the floor. Occasionally it will blow cold at a red light, but only for a minute or so. I put an AC manifold to it, the pressure is good. I jumpered the low pressure switch and still nothing. Soooo, does this AC system have a throttle position sensor and where is it located so I can jump it next. Like I said, I get ice cold air when the throttle is to the floor. As soon as I let up it begins to go warm.

Thanks in advance for any help. It's getting warm in TX.